A federal jury has deadlocked on a claim by a former trainer for Barry Bonds that a San Francisco police officer used excessive force by clubbing him and throwing him to the ground on a North Beach street in 2006.

But lawyers for the city say the jury unanimously rejected Greg Oliver's separate claim that the officer, Jesse Serna, arrested him illegally. They have asked U.S. Magistrate James Larson to dismiss that claim if Oliver seeks a retrial of his excessive-force suit, which sought $1 million in damages.

The case dates from August 2006, when Oliver, 35, of Scottsdale, Ariz., said he was waiting for a cab at Broadway and Kearny Street and saw three men attack another. He said police arrived, two of them tackled the victim and one of his assailants, and the third, Serna, hit Oliver in the chest with his baton for no reason.

Oliver said he had tried to tell Serna that police were attacking the wrong man, but the officer clubbed him twice on the thigh, then wrestled him to the ground and handcuffed him. He said Serna had twisted his wrist violently after cuffing it, and one of the other officers, whom he couldn't see, had stomped on his leg while he knelt.

Serna said he had arrived at the scene of the fight and told the crowd to keep back, but that Oliver had pressed forward aggressively and told him police had the wrong man. He said he had hit Oliver twice with the baton when Oliver continued to disobey orders, then had taken him to the ground. He denied twisting Oliver's wrist.

After a one-week trial, the jury was unable to reach a unanimous verdict April 17, and Larson declared a mistrial without polling the jurors. But Deputy City Attorney Scott Wiener said in a court filing this week that jurors had told him they came within one vote of rejecting all of Oliver's claims.

Wiener said he had spoken with a number of jurors after the mistrial, in the presence of one of Oliver's attorneys, and they had told him the vote was 9-0 to find that Serna had arrested Oliver legally for resisting arrest and that the other officers had not used excessive force. He said they had reported an 8-1 vote against the claim of excessive force by Serna.

Oliver's lawyer, John Burris, said Thursday he had no information on any such votes. He said Oliver hadn't decided on his next step.

Oliver was one of the personal trainers who worked with Bonds when the outfielder played for the Giants. At one point, Oliver was employed by the team.

Serna, 43, a police officer since 1995, was identified in a Chronicle analysis in 2006 as the San Francisco officer who reported the most instances of using force from 1996 through 2004 - 57 reports, causing 31 injuries.

The city has paid $195,000 in three lawsuits by individuals who accused Serna of using excessive force. He was taken off street duty in June 2007.